6 of 7 Question B2 a) Red light of vacuum wavelength 650 nm is travelling in non-magnetic glass with refractive index ng 1.50, then meets an interface with air at an angle of incidence of 75 degrees, and total internal reflection occurs. Calculate the tangential component of the wavevector KG in glass; state two conditions on the transmitted wavevector кA on the air side; and show that this leads to an evanes- cent wave with amplitude decaying exponentially away from the boundary. Calculate the distance over which the E-field amplitude drops by a factor of 1/e.

6 of 7 Question B2 a) Red light of vacuum wavelength 650 nm is travelling in non-magnetic glass with refractive index ng 1.50, then meets an interface with air at an angle of incidence of 75 degrees, and total internal reflection occurs. Calculate the tangential component of the wavevector KG in glass; state two conditions on the transmitted wavevector кA on the air side; and show that this leads to an evanes- cent wave with amplitude decaying exponentially away from the boundary. Calculate the distance over which the E-field amplitude drops by a factor of 1/e.